A previous patent obtained by the applicant herein, U.S. Pat. No. 4,114,208 entitled Water Closet Flush Valve covered an invention on a flush valve for a toilet and included a valve housing disposed within the tank, the housing being provided with a valve stem and piston arranged for independent vertical movement to define a valve for communicating the housing with a syphon so that water flowing through the valve induces a syphon action in the syphon to drain the water from the tank into the bowl for a flushing action. The housing communicates with a source of water through another valve actuated by the piston through which water for the syphoning action is obtained as well as providing a source of water for refilling the tank subsequent to the flushing action.
The flushing action in the invention of the aforementioned patent is initiated by the actuation of the toilet flush lever which rotates a cam into camming engagement with the piston separating the piston from the valve stem maintained in the uppermost position by the float and as the float moves downwardly as the water level in the tank drops engagement between the valve stem and piston closes the valve interrupting the syphoning action to permit the tank to be refilled through another valve associated with the valve housing. The rising water in the tank returns the valve stem to the upper position returning the parts to their original position interrupting the introduction of water into the tank.
While very satisfactory results have been obtained with the flush valve of the aforementioned patent, such as the conservation of water, leakproof construction, anti-syphon prevention and positive shut-off, further evaluation of the flush valve has indicated the need for various improvements for even greater efficiency in the operation of the valve.